A Preseason Training Program With the Nordic Hamstring Exercise Increases Eccentric Knee Flexor Strength and Fascicle Length in Professional Female Soccer Players.
Karoline Baptista Vianna, Lívia Gonçalves Rodrigues, Nathalia Trevisol Oliveira and 2 others
PMID 33842041WHAT IT FOUND
An 8-week Nordic hamstring program increased eccentric knee flexor strength by about 13% and fascicle length by about 7% in professional female soccer players.
Strength gains were larger than those typically seen in male athletes, but half the players did not show meaningful fascicle lengthening.
Key findings
01The 8-week Nordic hamstring exercise program significantly increased eccentric knee flexor strength in both limbs, with moderate to large effect sizes.
02Biceps femoris long head fascicle length increased significantly in both limbs, but the magnitude was smaller than strength gains and only about half of the players were classified as responders.
03Players who did not respond with increased strength also failed to increase fascicle length, suggesting individual non-response affects both adaptations.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The study was not randomized because the club required all players to participate in the preventive program, so other training changes during preseason cannot be ruled out as causes for the adaptations. The sample size was small (17 players), and the percentage of responders should be interpreted with caution. The study did not follow players into the season to determine if these adaptations actually reduced hamstring injury rates. The non-trained group was amateur players, not a matched control of professional players, limiting direct comparison of training effects versus no training in the same population.
Declared interests
The authors declare that there is no conflict of interest.
The easy way to misread this
Do not assume that the observed strength and fascicle length changes directly reduced hamstring injuries in these players. The study did not track injury rates during the subsequent season, and because there was no randomized control group, other aspects of preseason training may have contributed to the adaptations.